Improvement in tubular arch-girders for bridges and other structures



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DAVID HAMMOND AND JOB ABBOTT, 0F OANTONQOHIO.

Letters Patent o. 102,392, dated April 26, 1870.

.IMPROVEMENT IN TUBULAR ARCH-GIRDERS FOR BRIDGES AND OTHER STRUCTURES.

The Schedule referred to in these Letters Patent and making part gf' the lama.

.ro all lwhom it may concern:

Be it 'known that we, DAvrD HAMMoNp and JOB ABBOTT, both of' Canton, in the county of Stark and Statev of' Ohio, have invented certain new and useful Improvements in Tubular Arch-Girders and we do hereby declare that thel following is a full, clear, and exact description of that portion of said invention which we have designated as part A, reference being had to the accompanying drawings forming a part of' this specification, and to the letters of' reference marked thereon, of' which drawings- Figure l -is a plan showing several modifications of our girder.

Figure 2 is a sectional elevation of' the upper girder, shown in fig. 1. I

Figure 3 is an elevation of the'lower girder, shown in fig. 1.

Figures v4, 5, and 6 are cross-sections of the arches of girders shown in fig. 1.v

Figures 7 and 8 are'crossrsections of the girders shown in figs. 2 and 3. y

The nature of' our inventionrconsists in the construction of' a girder with an arch cornposedcssentially of' two pieces of rolled iron, having a curved or polygonal-shaped web, with flanges on each side, said arch-pieces heilig curvedl to the required curve for the` arch, and being placed parallel to each other in such a manner as that two flanges (one of'each piece) shall be in the saine curved horizontal plane, and said two principal arch-pieces being so combined withother archpieces as to form a tubular arc-h of` great strength and stiffness, which admits of a very economical distributicn and proportion of material to any required case of construction, and forms, when combined with suitable shoes, chords, posts, and braces, a very cheap and strong girder for bridgelconstruction, or other constructions of like character.k

To enable others skilled in the art to make and use our invention, we will proceed to describe more fully its application andconstruction.

The principal arch-pieces A A' are of the form shown. in fig. 4, being made with thc central web A of the circular cross-section shown, (or of a polygonal or other cross-section closely approaching a circular cross-secltion, if preferred,) and having a flange, a or a', on each and six feet width of. track. The arcl1.for 'such'girderl need not have a great crushing capacity, as the load to be carried can never be very great, but it must have great lateral capacity to resist a lateral bending ofthe arch, as the track is too narrow to admit of good lateral bracing without great expense. y

Accordingly, the broad plate B is used in combination with the arch-pieces A A, as shown in fig. 5, the flanges c a being riveted to said plate, as shown, and' the other flanges a a' being brought up to each other and riveted together, as shown in fig. 6, or they may4 be held apart by thirnbles, j; which are placed around the rivets which unite the flanges Aa c', as shown in fig. l, when a greater lateral capacity against bending is required, without an increase of cross-,section in the arch.

When both an increase of' lateral capacity and crushing -strength are required, the channel-bars H or L, as shown in fig. 4, may be used between the flanges afa',

` where they can v be secured either by two rows of rivets, one through each flange a' and a ange of' the channel-bar, or by a single row ofl long rivets passing through both flanges a' a' andthe flanges ofthe channel-bar, the first being the preferable mode of' lriveting.

Wewould here state that by the -terrn channelbar7 we designate any bar-iron with flanges of' suitable width at its edges, whether the web of such bar be plain or curved, or whether the fianges be at right angles to the plane of the web or not, the flanges ca' of' the arch-pieces A A being made to' conform to the inclination of the flanges oi' the channel-bar in each case.

In each of the above-described modifications it will be observed that the plate B forms the principal resistant to the lateral vbending of the arch, while thc arch-piecesAA, either directly in combination with `each other and the plate B, or in combination with the thimbles f or channel-bars H or L and the plate B, form a tube which is the principal resistant to the crushing strain-on the arch; and, furthe?, that by having the pieces A A`made with theirwebs of a curved or polygonal cross-section, the material is placed further away from` the axis ofthe tube forming the arch, and the crushingcapacity of such tube is consequently increased without any increase in its cross-section.

It will also be observed that the same capacities of material will be developed, whether the plate B be arranged below the arch-pieces A A, as shown in fig. 5, or Whether said arch-pieces be placed below said plate, in which case the cross-section shown in fig. 5 would be simply reversed.

For a second example,let it be required toconstruct a girder for a railroad bridge of one hundred and fifty feet span andtwelve feet width of track;

The arch for such a girder must have a large crosssection to resist crushing strain, as well as great lateral capacityto resist horizontal defiection, as the track is too narrow in proportion to the span and moving load to give good lateral bracing. Accordingly, we combine two sets of arch-pieces, A A A1 A1, as shown in figs. 2, 4, and 7, by riveting together the horizon-V tal flanges a a a a and uniting the upper and lower flanges a' a' a' a by rivets and thimbles f, or by channel-bars L, H, and K, or by combining these two methods, either by using a channel-bar along' the ends and on the upper side of the arch, in combination with pieces of'channel-bar riveted in at such points on the upper side as are toserve as `points of' attachment for the posts of the girder, with thimhles between such pieces and all along between the lower flanges of the arch; or a channel-bar may be used along the whole length of the upper or lower sides, or on both the upper and lower sides, as illustrated in iig. 2, the particular construction required depending very much on v. the amount of cross-section required in the arch, and

also on the amount of' lateral stability required, which must be determined on by the engineer in any particular case, and cannot, therefore, he definitely stated here.

For a third example, let it be required to construct l a girder 0r a common road bridge ot' one hundred and fifty feet span and twenty feet width of track.

The arch for such a gil-der need have but a moderate amount of crushing.cross-section, and the width ot' track is such that a good lateral bracing can be had; hence, the material in the arch should be so disposed as to give the greatest amount of' crushing strength with a proper amount of lateral stiffness.

Accordingly, we combine the two sets Ofarch-pie'ces The general ideas ot' the methods used in constructing the `arch having been thus f'ully shown, the manner of' completing the 'girder is readily seen, and differs in but few points from that shown ill other archgirders heretofore constructed. i l

The ends of' the arch rest on cast-iron shoes, C C, in which are formed seats for the heads D D of' one or more chords, E E, of fiat bar-iron, which imite thc ends of the arch.

The posts F F and the tie-rods G G may he formed with eyes at their lower ends, which are secured between the chords E E 'by bolts b b, as shown `vin figs. 2 and 7, while the upper ends of the saidposts and tie-rods are passed through the channel-bars H or L in the arch, and are secured by nuts c c andd (l, as shown.

If it is found desirable not to punch holes in the chords E for the bolts b, the posts F may be attached to said chords by means of' jam-nuts h h, which bind the clamping-piecesfi and j (through which are passed` the posts F') firmly to the chords E E, the tie-rods G" .shown in fig. 3, or by passing them through the web of the arch-pieces, as shown in fig. 8.

The tie-rods G1 may also be attached to the arch by means of' the plates N, riveted to the lower flanges c' a', and provided with an axial vrivet which passes through an eye nt the upper end of the tierod, as shown in fig. 3. V

A convenient mode of attaching both post and tierod tothe arch is shown in figs. 3 and S, where M represents a stirrup riveted to the flanges a a, and provided with a hole at its bottom, through which is passed the post I5".

The fie-rod GfZ is made with an eye, g, at its upper end, which fits over the. post F', and both post and tie-rod are secured by the nut c', as shown. 4

Having thus fully described our invention,

\Vhnt we claim as new, and desire to secure by Letters Patent, is-

l. The combination of the arch-pieces A A with curved webs A and edge flanges a f a a', thimblesf, or channel-hars H, and broad plate B, the several parts being arranged and united by rivets or their equivalents, sul'istantially'as and for the purpose specificd.

2. The combination of the arch-pieces A A with curvedwebs A and edge fianges a a aa', channel-bar H or L, arch-pieces A1 A1, with edge tlanges (t a u a and channel-bar K, the several' parts being arranged and combined by rivets or their equivalents, substantially as and for the purpose specified.

3. The combination of the arch-pieces A A with curved webs A and edge flanges aI a' c c', channel-bar H or L, arch-pieces A1 A1 with edge flanges a a. a a.' and thimbles f f, the several parts being arrangedand combined by rivets o'r their equivalents, substantially as and for the purpose described.

4. The combination of the arch, composed of the arch-pieces A A A1 A1, with curved or polygonal webs and edge flanges a a and channel-hars H and K, arch shoes C C, chords E E, posts F F, and tie-rods G G,

the several parts being arranged as and for the purpose specified. p

As evidence that we claim the foregoing, wehave hereunto set our hands in the presence of two witncsses, this 28th day ot June, 1869.

DAVID HAMMOND.

JOB ABBOTT. Witnesses:

J. P. TH. LANG, FRED. Antros'. 

